Grinding machine with a feed control device

ABSTRACT

In a grinding machine having a feed control device in which a first feed means is connected to a wheel support for performing grinding operations, a first grinding operation by the first feed means is controlled by a gauging member, and an advanced position thereof is memorized by a memory device. A second feed means is connected to the wheel support for compensating the same by a half of the difference in the diameters of a workpiece portion to be ground in the first grinding operation and of a second workpiece portion to be ground in a second grinding operation. The second grinding operation is controlled by a detecting means, whereby the first feed means is caused to be retracted when the first feed means comes up to the position memorized by the memory means in the first grinding operation.

United States Patent [1 1' Asano GRINDING MACHINE WITH A FEED CONTROLDEVICE Hiroaki Asano, Chiryu J apan Toyoda Koki Kabushiki Kaisha,Aichi-ken, Japan Filed: Mar. 20, 1972 Appl. No.: 236,477

[75] Inventor:

[73] Assignee:

References Cited UNITED STATES PATENTS 12/1941 Astrowiski ..5l/l65.9l3/1949 Marshall ..5l/165.9l

[ Oct. 30, 1973 Primary Examiner-Harold D. Whitehead Attorney-Norman F.Oblon et al.

57 ABSTRACT In a grinding machine having a feed control device in whicha first feed means is connected to a wheel support for performinggrinding operations, a first grinding operation by the first feed meansis controlled by a gauging member, and an advanced position thereof ismemorized by a memory device. A second feed means is connected to thewheel support for compensating the same by a half of the difference inthe diameters of a workpiece portion to be ground in the first grindingoperation and of a second workpiece portion to be ground in a secondgrinding operation. The second grinding operation is controlled by adetecting means, whereby the first feed means is caused to be retractedwhen the first feed means comes up to the position memorized by thememory means in the first grinding operation.

11 Claims, 11 Drawing Figures GRINDING MACHINE WITH A FEED CONTROLDEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention Thepresentinvention relates generally to grinding machines, and more particularlyto a feed control device for use in a grinding operation.

2. Description of the Prior Art When automatically successively grindingmultistepped portions of a workpiece in an automatically or anumerically controlled grinding machine, it is desirable to grind theworkpiece portions by using a gauging device which directly measureseach of the stepped workpiece portions. I

However, the application of a gauging device to a workpiece portionhaving slots or splines on the periphery thereof is not possible becausethe feelers of the gauging device drop into the slotted portions.

Accordingly, in a prior art device, dead stop machining has been appliedto such slotted workpiece portions or discontinuous round portions. Morespecifically, dead stop machining is an operation in which the rotatingend of a feed wheel is limited by a stop arrangement, and a workpiece ismachined to its desired finished dimension in a single stroke ofrotating the feed wheel up to the position of the stop.

However, because the position of the dead stop must be adjusted prior toall grinding operations, grinding wheel wear and machine elementdisplacement exerted during the grinding operations adversely affect thefinished diameter. of the workpiece portions.

Further, in order to automatically grind multistepped workpiece portionsin a dead stop machining operation, adjustments of the dead stop arenecessary for each of the work diameters.

Therefore dead stop machining processes as well known in the prior artare not applicable to the grinding of multi-stepped workpieces havingcontinuous and discontinuous round portions.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide a grinding machine with an improved control devicefor grinding wheel feeding.

Another object of the present invention is to provide a grinding machinewhich has an improved dead stop mechanism for eliminating the effects ofgrinding wheel wear and machine element displacement on a finishedworkpiece diameter.

A still further object of this invention is to provide a grindingmachine having a feed control device which automatically memorizes anadvanced position of the feed means in a previous grinding operation andautomatically controls a successive grinding operation to preciselygrind a workpiece portion according to the memorized reference position.

Yet another object of this invention is to provide a feed control devicefor a grinding machine which gives a grinding speed change signal uponreaching a predetermined work diameter and successively gives a sizesignal upon reaching the desired finished work diameter.

A yet further object is to provide a mechanism for.

The foregoing and other objects are attained by the present inventionaccording to one aspect thereof through the provision of an arm memberbeing connected to an infeed mechanism for being rotatably advanced andretracted thereby. A memory member following the advancing movement ofthe arm member is provided so as to memorize the advanced position ofthe infeed mechanism in a previous grinding operation. When the infeedmechanism and the arm member retract, the memory member is held at itsadvanced position by a locking member engaging the periphery portionthereof. Then, in the next grinding operation, a detecting membermounted on the memory member produces a sizing signal for controllingthe infeed mechanism when the arm member subsequently comes up to thememorized advanced position of the memory member.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features andattendant advantages of the present invention will be more fullyappreciated as the same becomes better understood from the followingdetailed description when considered in conjunction with theaccompanying drawings, wherein like reference numerals designate like orcorresponding parts throughout the several views and in which:

FIG. 1 is a diagram showing a grinding wheel stroke with regard to amulti-stepped workpiece;

FIG. 2 is a transverse cross-sectional view showing a grinding machinehaving a feed control device constructed according to the presentinvention;

FIG. 3 is an enlarged cross-sectional view showing the portion lyingwithin the circle III of FIG. 2;

FIG. 4 is a cross-sectional view taken on the line IV-IV in FIG. 3;

FIG. 5 is a cross-sectional view taken on the line V-V in FIG. 4; I

FIG. 6 is a fragmentary cross-sectional view taken along the line VI-VIin FIG. 3;

FIG. 7 is a diagram of a hydraulic circuit arrangement for controllingthe operation of the grinding machine of this invention;

FIG. 8 is an enlarged cross-sectional view of another embodiment showingthe portion lying within the same circle III of FIG. 2 as the embodimentof FIG. 3;

FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. 8,

FIG. 10 is a cross-sectional view taken along the line X-X in FIG. 8;and I FIG. 11 is a cross-sectional view taken along the line XI-XI inFIG. 9.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, andparticularly to FIG. 2 thereof, there is shown a bed 1 on which a slidebase 6 is mounted to slidably support an intermediate slide base 7.Slidably mounted on the intermediate slide base 7 is a wheel support 8for rotatably supporting a grinding wheel 9. Mounted in the slide base 6is a rapid feed hydraulic cylinder 11 having a piston 13 slidablyreceived therein anda piston rod 12 integrally formed with the piston13. The piston rod 12 integrally forms at one end thereof a coaxiallydisposed first feed screw 15 which threadably engages a feed nut 16depending from the lower surface of the intermediate slide base 7. Thefirst feed screw 15 is drivingly connected to a drive shaft 26 rotatablysupported in the bed 1 through a gear connection 27, 28 and 29.

Mounted on the intermediate slide base 7 is a pulsemotor 20 which may becontrolled in accordance with a tape command. A second feed screw shaft17 connected with the pulse-motor 20 is rotatably supported in theintermediate slide base 7, being threadably engaged at its screw portion18 with a feed nut 19 depending from the lower surface of the wheelsupport 8.

A work table 2 is slidably mounted on one end of the bed 1 for movementin a direction perpendicular to the path of movement of the wheelsupport 8 and pivotally supports a swivel table 100 thereon. On theswivel table 100, there is provided a head stock 3 and a foot stock, notshown, for supporting a workpiece B therebetween.

The swivel table 100 is also provided with a gauging device 4 having apair of feelers 5 for engaging the periphery of the workpiece B. Thegauging device 4 is operable to change the operation from a roughgrinding speed to a fine grinding speed at a predetermined workpiecediameter, and to retract the wheel support 8 when the workpiece isground to a predetermined size.

A manually operable feed wheel 22 is provided for imparting a rotarymotion to the first feed screw to advance the intermediate slide base 7together with the grinding wheel 9 and the wheel support 8 mountedthereon. The feed wheel 22 is mounted on a pinion shaft 101 rotatablysupported in the bed 1. The pinion shaft 101 keys a pinion 23 on theright end portion thereof to meshingly engage a pinion 24 fixed on thedrive shaft 26 by means of a pin 25.

A hydraulically operated infeed mechanism generally designated by thenumeral 31, as shown in FIGS. 2, 3 and 7, is provided for automaticallyactuating the first feed screw 15 and comprises a cylinder 33 in whichis slidably mounted a piston rod 32 and a piston 34. The piston rod 32is provided with rack teeth 36 which mesh with a gear 37 mounted on ashaft 102. The gear 37 meshes with a gear 38 integrally formed on acylindrical member 39 which is rotatably mounted on the drive shaft 26and is provided with another gear 46 on the left end portion. A clutchpiston 42 is slidably received in the cylindrical member 39 but isrestrained from rotation with respect thereto by means of a key member43. The clutch piston 42 has a conical surface 45 cooperativelyassociated with a conical surface 44 of the pinion 24. A spring 41 isdisposed between the clutch piston 42 and the pinion 24 for normallyurging them to move axially away from each other. Between the left endsurface of the clutch piston 42 and the bottom of a bore formed in thecylinder 39 in which the clutch piston 42 is received, a chamber 40 isformed.

Accordingly, when pressure fluid is admitted into the chamber 40, theclutch piston 42 and the pinion 24 are caused to be frictionallyengaged. This clutch mechanism is provided to facilitate disconnectingthe piston 34 during manual actuation of the feed mechanism.

It will be readily apparent that rotary motion of the first feed screw15 is imparted either by manual actuation of the feed wheel 22 throughshaft 101, pinions 23 and 24, shaft 26 and gears 27, 28 and 29, or byautomatic actuation of the infeed mechanism 31 through piston rod 32,rack 36, gears 37 and 38, cylinder 39, clutch piston 42, pinion 24 andshaft 26, to produce a transverse feeding movement of the wheel support8 and the grinding wheel 9 thereon through the slide base 7.

A feed control valve 77, as shown in FIG. 7, is provided for controllingthe admission to and the exhaust of fluid from the cylinder 33. Acompression spring 118 serves normally to hold the valve 77 in arightwardly disposed position, and a solenoid S3 is provided forshifting the valve 77 into its leftwardly disposed position. When thesolenoid S3 is energized, fluid under pressure passing through apressure line 119 from a source P enters the right end chamber 120 ofcylinder 33 through the right block of the valve 77 to move the piston34 and the piston rod 32 leftward for actuating a hydraulically operatedgrinding feed. At the same time, fluid in a left end chamber 121 of thecylinder 33 passes through both a fine feed throttle valve 123 and arough feed throttle valve 122, and through the feed control valve 77,into a reservoir 124.

The advance feed movement of the wheel support 8 is a faster feed speedsubstantially determined by the rough feed throttle valve 122.

When a speed change signal 126 is produced by the gauging device 4, or amemory device 103 described hereinafter, a speed change valve 128 isshifted leftward to close the circuit including the rough feed throttlevalve 122. Accordingly the speed of the grinding feed slows to a speeddetermined only by the fine throttle valve 123.

Referring now to FIGS. 3, 4, 5 and 6, there is shown a memory devicegenerally designated by the reference numeral 103, which includes acasing 106 secured to a bed cover 105 fixed on the bed 1. Fixedlysupported in the casing 106 is a supporting sleeve 104 which rotatablycarries a shaft 48 therein by means of spaced needle bearings. The shaft48 has on one end thereof a gear 47 meshingly engaging the gear 46 onthe cylindrical member 39 and on its other end has an arm member 49secured thereto by bolts or the like.

The arm member 49 is rotatably clockwise advanced and counterclockwiseretracted through the gearings 37, 38 and 46 and 47 by actuation of thefeed mechanism 31. the arm member 49 is provided, on its outer end andfacing in the rotating direction thereof, with a first nozzle 61 whereinpressure air may be supplied through conduits 64, 65, 65 and 66.Pressure air ejects from the first nozzle 61. A pressure switch 62 iscon nected to the conduit 66 to provide an electric signal upon thefirst nozzle 61 being closed and pressure in the conduits building up,as described hereinafter.

On the outer periphery of the supporting sleeve 104, a memory plate 56is rotatably mounted by means of a bearing bush 125, being axiallysecured by a collar 132 and a ring 133. The memory plate 56 is providedwith an integrally formed gear 54 on one end thereof which meshinglyengages rack teeth 53 on a rack piston 52, as shown best in FIG. 6. Therack piston 52 housed in the casing 106 is operable to be traversedtoward the right direction, as shown in FIG. 6, by the supplying ofpressure fluid in a chamber 107 so as to rotate the memory plate 56counterclockwise, as it appears in FIG. 4.

The memory plate 56 is provided with a bolted block member 72 having asecond nozzle 74 from which predetermined pressure air being suppliedthrough conduits 73, 69, 68 and 67 may be ejected.

A pressure switch is connected to the conduit 67 to provide an electricsignal whenever the second nozzle 74 is closed, as describedhereinafter.

A circular plate 76 is rotatably mounted on the one side of the memoryplate 56 and is axially held in place by the collar 132. The circularplate 76 has a block member 71 bolted thereon which is located betweenthe first and second nozzles 61 and 74. The block member 71 has twooperating faces 71b and 71a, respectively, to close the first and secondnozzles 61 and 74. The circular plate 76 is normally urged to rotatecounterclockwise with respect to the memory plate 56 by the force of aspring 87 connected therebetween and such rotation is restricted by anadjusting screw 58 which engages a stop pin 59 mounted on the memoryplate 56.

Accordingly the clearance 1 between the face 71a and the second nozzle74 is regulated to a predetermined distance by adjustment of theadjusting screw 58.

A shoe 57, as shown in FIG. 4, is slidably mounted in the casing 106 andis urged by the force of a spring toward the periphery of the memoryplate 56 to prevent free rotation thereof. This frictionally engagingforce of the shoe is weaker than the rotary force of the arm member 49and the rack piston 52, but is stronger than the force of the spring 87.

Thus, when the memory plate 56 is urged to rotate clockwise by the armmember 49 and counterclockwise by the rack piston 52, the shoe 57 cannotprevent the rotation. However, when the circular plate 76 clockwiserotates with respect to the memory plate 56 against the spring 87, theshoe 57 holds the memory plate 56.

' The operation of the improved control device for grinding wheel feedwill accordingly be readily apparent from the following disclosure.

A general description of an operation applied for a workpiece, as shownin FIG. 1, follows. Assuming a workpiece is mounted in the position fora grinding operation and the grinding wheel front face is adjusted at aposition A in FIG. 1, first a grinding operation will be be performed onthe work portion 8,, described hereinafter.

When a start switch, not shown, is actuated, a tape reader is actuatedto read a tape data. By a tape command from the tape reader, a solenoidS1, as shown in FIG. 7, is energized to'supply pressure fluid to a rearchamber of the rapid feed hydraulic cylinder 11 to cause a rapidadvancing movement of the intermediate slide base 7 together with thewheel support 8 and the grinding wheel 9.

Until the wheel support 8 reaches its rapid feed advance end position,pressure fluid is applied in the front chamber 121 of the infeedmechanism 31 and the chamber 107 of the memory device 103. Accordingly,the piston rod 32 is positioned to set the arm member 49 through thegearings at the set position shown by dotted lines in FIG. 4. On theother hand the rack piston 52 is urged rightward to rotate the memoryplate 56 counterclockwise toward the set position. Thereby the blockmember 71 and the circular plate 76 have been rotated counterclockwiseby the counterclockwise rotary movement of themernory plate 56 and urgedtoward the arm member 49 in the set position.

When the wheel support 8 is advanced to its rapid feed end, the feedcontrol valve 77 is shifted into its left end position to cause agrinding feed movement of the wheel support 8 at a speed determined bythe rough feed throttle valve 122. At the same time the feed strokeadjusting valve 51 is shifted into a left hand end position to admitfluid being exhausted from the chamber 107 so that rack piston 52 may beshiftable toward the left when an external force is applied thereto, ashereinafter described.

A grinding operation on the work portion B1 is achieved with the roughgrinding infeed. At the same time, the arm member 49 is rotatedclockwise in FIG. 4 through the gear connections by the infeed mechanism31. The arm member 49 engages the block member 71 to rotate it in anengaged state therewith. When block member 71 is rotated by a clearance1 the block member face 71a of the circular plate 76 engages the blockmember 72 of the memory plate 56. Accordingly, the memory plate 56 andthe circular plate 76 follow the rotary movement of the arm member 49 asa unit to be rotated together therewith.

During a grinding operation, the gauging device 4 engages the peripheralsurface of the work portion B to measure the work diameter. When theworkpiece is .ground to a predetermined size, the gauging device 4produces a speed change signal l26'to energize a solenoid S2 to shiftthe speed change valve 128 into its left end position to shut-off thecircuit including the rough feed throttle valve 122, whereby the feedspeed slows down in a slow pecise manner. Accordingly, the grindingspeed rate then is determined only by the fine feed throttle valve 123.

When the workpiece portion B is ground to a finished diameter D thegauging device 4 produces a size signal 131 to de-energize the solenoidsS1 and S3 to respectively admit pressure fluid into the front chambersof the rapid and infeed cylinders 11 and 33 to thereby traverse androtate the first feed screw 15 in the reverse direction to reset thefeed mechanism for the next grinding operation. Thus, the face A of thegrinding wheel 9 is retracted through a distance L.

During the reverse movement of the infeed mechanism 31 the arm member 49retracts to the position I a shown by the dotted lines in FIG. 4.

On the other hand the memory plate 56 is held at an advanced positionthereof by the shoe member 57 so as to memorize the advanced position ofthe infeed mechanism 31 in the present grinding operation. The memorizedadvanced position of the memory plate 56 serves in the production of asizing signal in the next grinding operation.

The former integration between the memory plate 56 and the circularplate 76 now discontinues because the pushing force by the arm member 49is released. More particularly, the circular plate 76 is rotatedcounterclockwise by the spring 87 until its rotation is restricted bythe stop pin for producing a predetermined clearance 1 between thesurface 71a and the second nozzle 74. This clearance 1 determines a finefeed grinding stroke for the next grinding operation and is adjustableby adjusting the screw 58.

In the memory device 103, when the first and second nozzles 61 and 74are. closed, the pressure switches 62 and 75, respectively, producechange speed and sizing signals. However, these signals are caused to beineffective by means of an electric circuit 127 in the operation using agauging device.

In a next step, the grinding operation is applied to a discontinuousround work portion B having a slot C. In accordance with the tapecommand, the work portion B2 is longitudinally positioned by the worktable 2 in front of the grinding wheel 9, and the pulse-motor 20 isrotated to retract the wheel support 8 with regard to the intermediateslide base 7 by a predetermined distance h, which equals a distancewhich is half the difference between the diameters D and D, of theworkpiece portions B and B The front surface of the grinding wheel 9 isshown at A in dotted line in FIG. 1. After that, the rapid feed cylinder11 is actuated to advance the intermediate slide base 7 together withthe wheel support 8 and the grinding wheel 9, and the infeed mechanism31 is actuated to perform a grinding operation on the work portion BHowever, the gauging device 4 remains in an inoperative position, thatis in a retracted position.

During the advancing movement of the piston rod 32 in the feed mechanism31, the arm member 49 is rotated in the clockwise direction from there-set position la toward the memorized advanced position lb of theblock member 71, as shown in FIG. 4. When the arm member 49 contacts theface 711; of the block member 71, the first nozzle 61 is closed to causethe pressure switch 62 to produce a speed change signal 126 which servesfor shifting the speed change valve 128 leftward to render the roughfeed throttle valve 122 ineffective. Accordingly, the infeed mechanism31 continues a grinding operation at a precise speed rate determinedonly by the fine feed throttle valve 123.

During the grinding operation performed at this precise speed rate, thearm member 49 also continues to rotate clockwise to urge the blockmember 71 in the same direction, but the memory plate 56 remains in theposition memorized in the previous grinding operation. When the armmember 49 is further rotated by the clearance I after engagement withthe block member 71, the second nozzle 74 is closed by the face 71a ofthe block member 71 to cause the pressure switch 75 to produce a sizingsignal. This sizing signal serves to deenergize the solenoids S1 and S3,thereby shifting the rapid feed valve 129 and the feed control valve 77toward the right. Accordingly, the wheel support 8 and the infeedmechanism 31 rapidly retract into the re-set position.

Thus, the work portion B is finished to the size D, by the sizing signalwhich is produced at the position memorized in the previous grindingoperation.

A grinding operation to a slotted work portion is controlled by a deadstop memorized in the previous grinding operation using a gaugingdevice.

Referring now to FIGS. 8, 9, l and l 1, details of another embodimentaccording to the invention are described, the members thereof whichfunction the same as in the previous embodiment being designated by thesame reference numerals.

The memory plate 56 in this embodiment is provided for rotatablysupporting a first block member 81 on the left side portion thereof andin concentric relation therewith. On the left side portion of the firstblock member 81 is rotatably mounted a second block member 82 which isconnected with the first block member 81 by means of a lever 84. Thefirst block member 81 is provided with an operating surface 91 forclosing the second nozzle 74, which when closed makes the secondpressure switch 75 exhibit an electric signal. The second block member82 is provided with an operating surface 92 for closing the first nozzle61 provided on the arm member 49, which when closed makes the firstpressure switch 62 give an electric signal.

The lever 84 is pivotally mounted on the memory plate 56 at pin 83,which is positioned on a line which is perpendicular to the axis 90 onthe line connecting the axis 90 and the second nozzle 74. The lever 84is 1 provided with a sphere-headed portion 85 at the end thereof and astud 88 threaded down at the intermediate portion thereof. The first andsecond block members are connected to each other in such a manner thatthe sphere potion 85 and the stud 88 are respectively engagedly receivedin a slot portion 86 provided in the first block member 81 and a slotportion 89 provided in the second block member 82.

The above-mentioned block assembly is urged in the counterclockwisedirection as seen in FIGS. 9 and 10, by the spring 87 connected betweenthe first block member 81 and the memory plate 56, and its movement isprevented by the adjusting screw 58 engaging the second block member 82.

When the second block member 82 is rotatably urged clockwise by the armmember 49, the movement thereof is magnified and transmitted to thefirst block member 81 by means of the lever 84. More particularly, whenthe second block member 82 rotates clockwise, the slot portion 89therein rotates the lever 84 counterclockwise around the axis 83. Themovement of the lever 84 is magnified in proportion to the lever ratioand is transmitted to the first block member 81 to rotate the sameclockwise through the engagement of the sphere headed portion 85 thereofwith the slot 86 of the first block member 81.

A magnifying rate may be shown as d f ld f in which d and d arerespectively the radii extending from the axis 90 to the sphere 85 andthe stud 88, f is the distance between the stud 88 and the axis 83, andf, is the distance between the sphere 85 and the axis 83.

The operation of the second embodiment will be readily apparent from theforegoing disclosure referring to the previous disclosure about thefirst embodiment.

When the previous grinding operation has been performed on the workportion 8,, the advanced position of the infeed mechanism 31 ismemorized by the memory device 103 as a position of the memory plate 56being securely held by the shoe 57. Fluid in the chamber 107 of thememory device 103 is exhausted to the reservoir, as shown in FIG. 7. Thepiston 34 in the infeed mechanism 31 is thus located in the right endposition and thereby the arm member 49 is positioned in the re-setposition la shown in FIG. 9.

The block assembly is rotated counterclockwise by the spring 87 tothereby produce a clearance l which serves as a fine feed stroke and isadjustable by the adjusting screw 58.

After compensation by the pulse-motor of the differential diameterbetween D2 and D1, grinding operation is performed on the work portionB, having the slot C.

The rapid feed cylinder 11 is actuated to advance the grinding wheel 9.After that, the infeed mechanism 31 is actuated to grind the workportion B, in a rough feed. During the rough grinding operation, the armmember 49 is rotated in clockwise direction from the re-set position latoward the position lb.

When the arm member 49 contacts with the operating surface 92 of thesecond block member 82, the first nozzle 61 is closed to cause thepressure switch 62 to produce a speed change signal to thereby reducethe speed of the infeed mechanism 31 to perform a fine grindingoperation. During fine grinding operation, the arm member 49 alsocontinues clockwise to rotate the block assembly, the movement of thesecond block member 82 being magnified and transmitted to the firstblock member 81. When the first block member 81 is rotated by theclearance 1 the second nozzle 74 is closed by the operating surface 91of the first block member 81 to cause the second pressure switch 75 toproduce a sizing signal. This sizing signal serves for rapidlyretracting the wheel support 8 and the infeed mechanism 31.

A differential transformer or an air switch may generally be used todetect the advanced position of the first block member 81. In such adetecting device, a differential gap must be considered. The air switchhaving an air nozzle and a pressure switch, as used in the presentembodiment, produces a sizing signal before the first block member 81completely closes the second nozzle 74, because when the first blockmember 81 approaches the nozzle 74, back pressure exerted in the secondnozzle 74 and the conduit thereto reaches a level to actuate thepressure switch. The gap between the front surface of the nozzle and theposition actuating the pressure switch is called a differential gap. Thedifferential gap affects the finished size of the workpiece to therebyresult in grinding of the workpiece such that it is larger than thepredetermined finished size.

In the second embodiment, the effect of the differential gap isminimized in inverse proportion to the magnifying rate d f /d f,.

Obviously many modifications and variations of the present invention arepossible in light of the above teachings. It is to be understood,therefore, that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described herein.Accordingly,

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A grinding machine for automatically successively grinding aworkpiece which comprises:

a bed;

a work table for rotatably supporting a workpiece;

a wheel support slidably mounted on said bed for rotatably supporting agrinding wheel; infeed means connected to said wheel support foradvancing and retracting said wheel support;

gauging means for measuring the work diameter to provide control signalsat predetermined diameters of said workpiece for controlling said infeedmeans; and

feed control means comprising displaceable means connected to saidinfeed means for being advanced and retracted proportionately with themovement thereof, memory means advanceable by said displaceable means inengagement therewith, and holding means for holding said memory means atan advanced position to memorize said advanced position of said infeedmeans controlled by said gauging means in previous grinding operation,whereby in the next grinding operation an advancing position of saidinfeed means is restricted by said advanced position of said memorymeans.

2. A grinding machine according to claim 1, wherein said feed controlmeans further comprises detecting means mounted on said memory means forproducing a control signal for controlling said infeed means when saiddisplaceable means comes up to said memorized advanced position of saidmemory means.

3. A grinding machine according to claim 2, wherein said detecting meanscomprises an air nozzle for producing a control signal when actuated bysaid displaceable means.

4. A grinding machine for automatically successively grinding aworkpiecewhich comprises:

a bed;

a work table;

a wheel support slidably mounted on said bed to rotatably support agrinding wheel;

infeed means connected to said wheel support for advancing andretracting said wheel support toward a workpiece;

gauging means for measuring the work diameter to produce control signalsat predetermined diameters of said workpiece for controlling said infeedmeans; and

feed control means comprising an arm member connected to said infeedmeans for being rotatably advanced and retracted proportionately withthe movement thereof, memory means rotatably engageable with said armmember for following the same to an advancing position of rotationthereof, a locking member engaging said memory means to hold said memorymeans at an advanced position to memorize said advanced position of saidfeed means controlled by said gauging means in a previous grindingoperation, and a first detecting member mounted on said memory means toexert a control signal for controlling said infeed means when said armmember comes up to said memorized advanced position of said memorymeans.

5. A grinding machine according to claim 4, wherein said memory meansfurther comprises:

a memory plate having said first detecting member thereon;

a circular plate rotatably mounted on said memory plate and having apair of operating surfaces; and

means flexibly holding said circular plate with a predeterminedclearance between one of said operating surfaces and said detectingmember so that one of said operating surfaces actuates said detectingmember to retract said wheel support when said circular plate is movedthrough said predetermined clearance by said arm member engaging theother of said operating surfaces.

6. A grinding machine according to claim 5, wherein said arm member hasa second detecting member for producing a speed change signal for saidinfeed means when said arm member comes up to the other operatingsurface of said circular plate.

7. A grinding machine according to claim 4, wherein said memory meanscomprises:

a memory plate having said detecting member thereon;

a first block member having a first operating surface and beingrotatably mounted on said memory plate;

means flexibly holding said first block member with a predeterminedclearance between said operating surface and said first detectingmember;

a second block member having a second operating surface and beingmounted on said memory plate; and

connecting means for connecting said second block member to said firstblock member, whereby said first operating surface actuates saiddetecting member to retract said wheel support when said first blockmember is moved through said predetermined clearance through saidconnecting means by said arm member engaging said second operatingsurface of said second block member.

8. A grinding machine according to ,claim 7, wherein said connectingmeans is a lever for magnifying rotary movement of said second blockmember and transmitting said movement to said first block member.

9. A grinding machine according to claim 8, wherein said arm member hasa second detecting member for producing a speed change signal forcontrolling said infeed means when said arm member comes up to saidsecond operating surface,

10. A grinding machine according to claim 8, wherein said lever ispivotally mounted on an outer portion of said memory plate, and isprovided at the inner end thereof with a sphere portion for engagingsaid second block member, and at an intermediate portion thereof with astud for engaging said first block member.

1 1. In a grinding machine for successively performing a plurality ofgrinding operations on a workpiece havfor compensating the same by ahalf of the diameter difference between said first work portion and asecond work.portion to be ground in a second grinding operation; and

second control means for retracting said first feed means to grind saidsecond work portion to a predetermined dimension in said second grindingoperation when said first feed means come up to the position memorizedby said memory means in said first grinding operation.

1. A grinding machine for automatically successively grinding aworkpiece which comprises: a bed; a work table for rotatably supportinga workpiece; a wheel support slidably mounted on said bed for rotatablysupporting a grinding wheel; infeed means connected to said wheelsupport for advancing and retracting said wheel support; gauging meansfor measuring the work diameter to provide control signals atpredetermined diameters of said workpiece for controlling said infeedmeans; and feed control means comprising displaceable means connected tosaid infeed means for being advanced and retracted proportionately withthe movement thereof, memory means advanceable by said displaceablemeans in engagement therewith, and holding means for holding said memorymeans at an advanced position to memorize said advanced position of saidinfeed means controlled by said gauging means in previous grindingoperation, whereby in the next grinding operation an advancing positionof said infeed means is restricted by said advanced position of saidmemory means.
 2. A grinding machine according to claim 1, wherein saidfeed control means further comprises detecting means mounted on saidmemory means for producing a control signal for controlling said infeedmeans when said displaceable means comes up to said memorized advancedposition of said memory means.
 3. A grinding machine according to claim2, wherein said detecting means comprises an air nozzle for producing acontrol signal when actuated by said displaceable means.
 4. A grindingmachine for automatically successively grinding a workpiece whichcompriseS: a bed; a work table; a wheel support slidably mounted on saidbed to rotatably support a grinding wheel; infeed means connected tosaid wheel support for advancing and retracting said wheel supporttoward a workpiece; gauging means for measuring the work diameter toproduce control signals at predetermined diameters of said workpiece forcontrolling said infeed means; and feed control means comprising an armmember connected to said infeed means for being rotatably advanced andretracted proportionately with the movement thereof, memory meansrotatably engageable with said arm member for following the same to anadvancing position of rotation thereof, a locking member engaging saidmemory means to hold said memory means at an advanced position tomemorize said advanced position of said feed means controlled by saidgauging means in a previous grinding operation, and a first detectingmember mounted on said memory means to exert a control signal forcontrolling said infeed means when said arm member comes up to saidmemorized advanced position of said memory means.
 5. A grinding machineaccording to claim 4, wherein said memory means further comprises: amemory plate having said first detecting member thereon; a circularplate rotatably mounted on said memory plate and having a pair ofoperating surfaces; and means flexibly holding said circular plate witha predetermined clearance between one of said operating surfaces andsaid detecting member so that one of said operating surfaces actuatessaid detecting member to retract said wheel support when said circularplate is moved through said predetermined clearance by said arm memberengaging the other of said operating surfaces.
 6. A grinding machineaccording to claim 5, wherein said arm member has a second detectingmember for producing a speed change signal for said infeed means whensaid arm member comes up to the other operating surface of said circularplate.
 7. A grinding machine according to claim 4, wherein said memorymeans comprises: a memory plate having said detecting member thereon; afirst block member having a first operating surface and being rotatablymounted on said memory plate; means flexibly holding said first blockmember with a predetermined clearance between said operating surface andsaid first detecting member; a second block member having a secondoperating surface and being mounted on said memory plate; and connectingmeans for connecting said second block member to said first blockmember, whereby said first operating surface actuates said detectingmember to retract said wheel support when said first block member ismoved through said predetermined clearance through said connecting meansby said arm member engaging said second operating surface of said secondblock member.
 8. A grinding machine according to claim 7, wherein saidconnecting means is a lever for magnifying rotary movement of saidsecond block member and transmitting said movement to said first blockmember.
 9. A grinding machine according to claim 8, wherein said armmember has a second detecting member for producing a speed change signalfor controlling said infeed means when said arm member comes up to saidsecond operating surface.
 10. A grinding machine according to claim 8,wherein said lever is pivotally mounted on an outer portion of saidmemory plate, and is provided at the inner end thereof with a sphereportion for engaging said second block member, and at an intermediateportion thereof with a stud for engaging said first block member.
 11. Ina grinding machine for successively performing a plurality of grindingoperations on a workpiece having multi-stepped portions: a bed; a worktable for rotatably supporting a workpiece; a wheel support slidablymounted on said bed to rotatably support a grinding wheel; first feedmeans connected to said wheel support for performing grindingoperations; control means for controlling said first feed means to grinda first work portion to a predetermined dimension in a first grindingoperation; memory means for memorizing an advanced position of saidfirst feed means controlled by said control means in said first grindingoperation; second feed means connected to said wheel support forcompensating the same by a half of the diameter difference between saidfirst work portion and a second work portion to be ground in a secondgrinding operation; and second control means for retracting said firstfeed means to grind said second work portion to a predetermineddimension in said second grinding operation when said first feed meanscome up to the position memorized by said memory means in said firstgrinding operation.